EFFECT OF ASCOCHYTA BLIGHT (MYCOSPHAERELLA-PINODES) ON YIELD COMPONENTS OF SINGLE PEA (PISUM-SATIVUM) PLANTS UNDER FIELD CONDITIONS

Field studies were made in 1992 and 1993 to examine the yield componen ts of pea inoculated with Mycosphaerella pinodes and those of healthy pea (sprayed with a mixture of flutriafol + chlorothalonil), in a spli t-plot design with the cv. Solara sown at different plant densities. A scochyta blight was severe on leaves and on internodes of the basal pa rt of the plants; pods had few lesions. The number and length of stems per plant were the same for diseased and healthy plants. The number o f reproductive nodes and pods per stem were affected by disease only i n 1993. In 1992 and 1993 respectively, disease caused reductions in th e number of seeds per stem of 18% and 25%, and in seed size of 13.5% a nd 16.7%, compared with healthy plants. The harvest index and total bi omass were lower in diseased than in healthy plants and seed yield was reduced by 40% in diseased plots. These results show a high relations hip between the disease parameters (disease mean on stipules/nodes 8-1 8/ and on internodes/nodes 5-15/, percentages of stipules or internode s with a disease score greater than or equal to 4, and percentage of s tems encircled by lesions), plant density and yield reduction.